Energy storage system



FIG. 1 is a front view of the claimed design;

FIG. 2 is a rear view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof;

FIG. 7 is a perspective view thereof; and,

FIG. 8 is a second front view thereof, with a cover removed.

The broken lines in the figures depict portions of the energy storage system which form no part of the claimed design. 

CLAIM I claim the ornamental design for an energy storage system, as shown and described. 